Two-part accommodating intraocular lens device

ABSTRACT

A two-part accommodating intraocular lens (IOL) device for implantation in a capsular bag of a patient&#39;s eye. The IOL device includes a primary lens assembly and a power changing lens. The primary lens assembly includes a fixed lens and a peripherally disposed centration member. The centration member has a circumferential distal edge and a first coupling surface adjacent the circumferential distal edge. The power changing lens has an enclosed, fluid- or gel-filled lens cavity and haptic system disposed peripherally of the lens cavity. The haptic system has a peripheral engaging edge configured to contact the capsular bag and a second coupling surface. The first and second coupling surfaces are in sliding contact with one another to permit movement of the power changing lens relative to the primary lens assembly and also to maintain a spaced relationship between the fixed lens and the lens cavity during radial compression of the power changing lens.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 15/144,544, filed May 2, 2016, which is a continuation of International Patent Application No. PCT/US2014/063538 filed Oct. 31, 2014, which claims the benefit of Provisional Patent Application No. 61/899,110 filed Nov. 1, 2013, both of which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The invention relates generally to an accommodating intraocular lens device and, more particularly, to an accommodating intraocular lens device configured for implantation in a lens capsule of a subject's eye.

BACKGROUND

Surgical procedures on the eye have been on the rise as technological advances permit for sophisticated interventions to address a wide variety of ophthalmic conditions. Patient acceptance has increased over the last twenty years as such procedures have proven to be generally safe and to produce results that significantly improve patient quality of life.

Cataract surgery remains one of the most common surgical procedures, with over 16 million cataract procedures being performed worldwide. It is expected that this number will continue to increase as average life expectancies continue to rise. Cataracts are typically treated by removing the crystalline lens from the eye and implanting an intraocular lens (“IOL”) in its place. As conventional IOL devices are primarily focused for distance visions, they fail to correct for presbyopia and reading glasses are still required. Thus, while patients who undergo a standard IOL implantation no longer experience clouding from cataracts, they are unable to accommodate, or change focus from near to far, from far to near, and to distances in between.

Surgeries to correct refractive errors of the eye have also become extremely common, of which LASIK enjoys substantial popularity with over 700,000 procedures being performed per year. Given the high prevalence of refractive errors and the relative safety and effectiveness of this procedure, more and more people are expected to turn to LASIK or other surgical procedures over conventional eyeglasses or contact lens. Despite the success of LASIK in treating myopia, there remains an unmet need for an effective surgical intervention to correct for presbyopia, which cannot be treated by conventional LASIK procedures.

As nearly every cataract patient also suffers from presbyopia, there is convergence of market demands for the treatment of both these conditions. While there is a general acceptance among physicians and patients of having implantable intraocular lens in the treatment of cataracts, similar procedures to correct for presbyopia represent only 5% of the U.S. cataract market. There is therefore a need to address both ophthalmic cataracts and/or presbyopia in the growing aging population.

BRIEF SUMMARY

The two-part accommodating IOL devices disclosed herein provides for a number of advantages owing to its separate two-part construction. Implantation of the IOL device requires a significantly reduced incision size, as the two parts of the IOL device are implanted separately and thus significantly reducing the delivery profile for implantation. The reduced incision size provides for a number of advantages, including obviating the need for anesthesia and sutures to close the incision site and improved surgical outcomes.

Additionally, greater control is afforded with respect to adjusting the sizing and the power of the IOL during surgery. Implanting the primary lens into the lens capsule will provide the physician an impression as to the size of the patient's lens capsule and will thus help verify the correct size of the power changing lens that will subsequently be implanted.

In one embodiment, a two-part accommodating intraocular lens (IOL) device for implantation in a capsular bag of a patient's eye is described. The IOL device comprises a primary lens assembly and a power changing lens assembly. The primary lens assembly comprises a fixed lens and a centration member disposed peripherally of the fixed lens. The centration member has a circumferential distal edge and a first coupling surface adjacent the circumferential distal edge. The power changing lens comprises an enclosed and fluid- or gel-filled lens cavity and a haptic system disposed peripherally of the lens cavity. The haptic system has a peripheral engaging edge configured to contact the capsular bag and a second coupling surface facing the first coupling surface and located adjacent the peripheral engaging edge. The first and second coupling surfaces are in sliding contact with one another to permit movement of the power changing lens relative to the primary lens assembly. The first and second coupling surfaces maintain a spaced relationship between the fixed lens and the lens cavity when the power changing lens is radially compressed.

In accordance with a first aspect, a diameter d₁ of the power changing lens is greater than a diameter d₂ of the primary lens assembly in the absence of radial compression.

In accordance with a second aspect, the fixed lens does not change shape or curvature during accommodation.

In accordance with a third aspect, the lens cavity changes both shape and curvature during accommodation.

In accordance with a fourth aspect, the fixed lens and the lens cavity are positive power lenses.

In accordance with a fifth aspect, the fluid- or gel-filled lens cavity is a biconvex lens.

In accordance with a sixth aspect, the fixed lens assembly comprises a squared edge located circumferentially around the fixed lens outside of the optical zone.

In accordance with a seventh aspect, the facing surfaces of the centration member and the haptic system each comprise one of a complementary and interlocking pair, the interlocking pair being disposed circumferentially around the fixed lens and the power changing lens, respectively.

In accordance with an eighth aspect, the peripheral engaging edge is thicker than the circumferential distal edge.

In accordance with a ninth aspect, the thickness ratio of the circumferential distal edge to the peripheral engaging edge is in the range of about 1:5 to about 1:2.

In accordance with a tenth aspect, the primary lens assembly has a higher Young's modulus of elasticity than the power changing lens.

In accordance with an eleventh aspect, at least one of the centration member and the haptic system comprises a plurality of openings.

In accordance with a twelfth aspect, the power changing lens is comprised of two opposing surfaces which are displaced away from each other upon the application of a radial force along a peripheral edge, the two opposing surfaces having central and peripheral regions and a gradually increasing thickness profile from the peripheral to the central regions.

In another embodiment, a two-part accommodating intraocular lens (IOL) device for implantation in a capsular bag of a patient's eye is described. The IOL comprises a primary lens assembly and a power changing lens assembly. The primary lens assembly comprises a fixed lens and a centration member disposed peripherally of the fixed lens. The centration member has a radially-compressible peripheral edge having an outer circumferential surface configured to engage the capsular bag of the patient's eye and an inner circumferential surface spaced radially inward of the outer circumferential surface. The power changing lens comprises an enclosed and fluid- or gel-filled lens cavity and a haptic system disposed peripherally of the lens cavity. The haptic system has a circumferential edge configured to engage the inner circumferential surface. Radial compression applied to the outer circumferential surface causes at least one of an increase in curvature and a decrease in diameter of the lens cavity and radial compression applied to the outer circumferential surface does not cause an increase in curvature or a decrease in diameter of the fixed lens.

In accordance with a first aspect, the centration member further comprises circumferential hinges between the fixed lens and the peripheral edge, the circumferential hinges being disposed on opposing sides of the centration member.

In accordance with a second aspect, the centration member further comprises a single circumferential hinge between the fixed lens and the peripheral edge.

In accordance with a third aspect, the circumferential hinge is disposed on an inner surface of the haptic facing the power changing lens.

In accordance with a fourth aspect, the circumferential edge of the haptic system and the inner circumferential surface of the peripheral edge have complementary rounded surfaces and radial compression applied to the outer circumferential surface cause the peripheral edge to tilt radially inwardly about the circumferential hinge.

In accordance with a fifth aspect, the power changing lens is entirely contained within the peripheral edge of the primary lens assembly.

In accordance with a sixth aspect, the power changing lens further comprises a circumferential lip disposed radially inwardly of the inner surface of the circumferential edge.

In accordance with an seventh aspect, the power changing lens is comprised of two opposing surfaces which are displaced away from each other upon the application of a radial force along a peripheral edge, the two opposing surfaces having central and peripheral regions, wherein the region has a thickness that is at least two times, preferably at least three times, and most preferably at least 4 times greater than a thickness of the peripheral region.

In a further embodiment, a method for implanting a two-part IOL device in a capsular bag of a patient's eye is described. The method comprises first inserting and positioning a primary lens assembly in the capsular bag of the patient's eye through an incision located in the cornea, the primary lens having a fixed lens and a centration member disposed peripherally of the fixed lens. The next step comprises inserting and positioning a power changing lens in the capsular bag of the patient's eye anteriorly of the primary lens assembly, the power changing lens comprising an enclosed and fluid- or gel-filled lens cavity and a haptic system disposed peripherally of the lens cavity, the haptic system having a peripheral engaging edge configured to contact the capsular bag. The primary lens assembly is in contact with a posterior portion of the capsular bag and the power changing lens is in contact with the anterior portion of the capsular bag after implantation. The fixed lens and the lens cavity are centered about an optical axis.

In accordance with a first aspect, the incision is less than 5 mm, preferably less than 4 mm, and most preferably less than 3 mm.

In accordance with a second aspect, both of the inserting steps are performed through the incision.

In accordance with a third aspect, the method further comprises injecting a viscoelastic material before the inserting and positioning of the power changing lens.

Other objects, features and advantages of the described preferred embodiments will become apparent to those skilled in the art from the following detailed description. It is to be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the present disclosure are described herein with reference to the accompanying drawings, in which:

FIG. 1 is an exploded perspective view of an embodiment of the two-part accommodating IOL.

FIG. 2 is an exploded side cross-sectional view of the two-part accommodating IOL of FIG. 1.

FIG. 3 is an assembled side view of the two-part accommodating IOL of FIG. 1, in which the power changing lens and the primary lens are in sliding contact with one another.

FIG. 4A through 4F are a cross-sectional view of various embodiments of the two-part accommodating IOL.

FIG. 5 is an exploded perspective view of an embodiment of the two-part accommodating IOL.

FIGS. 6A and 6B are a top and side plan views of the power-changing lens of the two-part IOL of FIG. 5.

FIGS. 7A and 7B are top and side plan views of the primary lens of the two-part IOL of FIG. 5.

FIGS. 8A and 8B are exploded and coupled cross-sectional views of another embodiment of a two-part accommodating IOL in which the power changing lens and the primary lens are coupled together.

FIGS. 9A and 9B are cross-sectional views of alternate embodiments of a two-part accommodating IOL in which the power changing lens and the primary lens are coupled together.

FIGS. 10A and 10B are exploded and coupled cross-sectional views of a further embodiment of a two-part accommodating IOL in which the power changing lens and the primary lens are coupled together.

FIGS. 11A through 11F are top views of various alternate embodiments of the primary lens.

Like numerals refer to like parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Specific, non-limiting embodiments of the present invention will now be described with reference to the drawings. It should be understood that such embodiments are by way of example and are merely illustrative of but a small number of embodiments within the scope of the present invention. Various changes and modifications obvious to one skilled in the art to which the present invention pertains are deemed to be within the spirit, scope and contemplation of the present invention as further defined in the appended claims.

FIGS. 1-3 depict an embodiment of a two-part accommodating IOL device 100 in which the power changing lens 110 and the primary lens 120 are in sliding contact with one another.

The power changing lens 110 is depicted as comprising a fluid- or gel-filled lens chamber 112 and a haptic system 114 disposed peripherally of the fluid- or gel-filled lens chamber 112. The haptic system 114 comprises a peripheral engaging edge 116 that is configured to engage the capsular bag of the patient's eye, generally at a location where it is attached via zonules to the ciliary muscles. A plurality of through holes 115 may be disposed along the circumference of the haptic system 114 to reduce material bulk and thus the delivery profile of the power changing lens 110.

The primary lens 120 is depicted as comprising a fixed-power lens 122 and a plurality of centration members 124 disposed symmetrically about the fixed-power lens. The centration member 124 comprises a distal edge 126 and through holes 125 to reduce the resistance to radial compression exerted by the capsular bag.

The presence of the holes 115 in the power lens 110 allows the manipulation of both the power lens 110 and the primary lens 120 underneath it. The holes 115 also help reduce the delivery profile of the power lens 110 and permits both the power lens 110 and the primary lens 120 to be manipulated to center it in the capsular bag during implantation. The presence of holes 115 may also reduce the rigidity of the power lens. Similarly, the primary lens 120 also has holes 125 that permit manipulation and reduce delivery profile. The holes 125 of the primary lens 120 are additionally shaped so as to reduce the likelihood of grabbing the power changing lens 110 when the power changing lens 110 is implanted into the capsular bag of the patient's eye after the primary lens 120 has already been implanted.

The power changing lens 110 and the primary lens 120 is configured to be in sliding contact with one another, while maintaining a separation between the fluid- or gel-filled lens chamber 112 and the fixed-power lens 122. In one embodiment, this distance is maintained by angling either one or both of the haptic system 114 and the centration member 124 towards one another. As shown in FIGS. 2 and 3, the sliding contact between the power changing lens 110 and the primary lens 120 is made at the first and second coupling surfaces 118, 128, respectively.

The power changing lens 110 is sized and shaped to take on and respond to the radially-inward forces which are applied along the peripheral edge 116 of the lens 110. In contrast, the primary lens 120 does not participate in providing an accommodative response and thus is sized and shaped so as to avoid interfering or resisting the radial compressive forces that are applied to the power changing lens 110. This may be accomplished by controlling the relative diameters and thicknesses of the power changing lens 110 and the primary lens 120 to maximize the extent to which the radial compressive forces are applied onto the power changing lens 110 and to minimize the extent to which these forces are applied onto the primary lens 120.

In a preferred embodiment, as depicted in FIG. 2, the thickness t₁ of peripheral engaging edge 116 of the power changing lens 110 is substantially thicker than the thickness t₂ of the distal edge 126 of the fixed-power lens 122. In a preferred embodiment, the thickness ratio of t₁ to t₂ is 2:1, preferably 3:1, more preferably 4:1 and most preferably 5:1. In another preferred embodiment, as depicted in FIG. 3, the diameter d₁ of the power changing lens 110 is greater than the diameter d₂ of the primary lens 120.

In one preferred embodiment, at least the opposing sides or walls of the lens chamber 112 is made of a material of sufficient mechanical strength to withstand physical manipulation during implantation, but is of sufficiently low Young's modulus so as to minimize its resistance to deformation. In a preferred embodiment, the opposing sides of the lens chamber 112 is made of a polymer having a Young's modulus of 100 psi or less, preferably 75 psi or less, and most preferably 50 psi or less. In one preferred embodiment, the remaining portions of the IOL 100 has a Young's modulus that is greater than the Young's modulus of the lens chamber 112. The walls of the lens chamber 112 may be a polymer, preferably a silicone polymer and more preferably a phenyl siloxane, such as a vinyl-terminated phenyl siloxane or a vinyl-terminated diphenyl siloxane. In order to impart sufficient mechanical strength, the polymer may be crosslinked, reinforced with fillers, or both. The fillers may be a resin or silica that have been functionalized to react with the polymer.

The walls of the lens chamber 112 define an enclosed cavity that is filled with a fluid or gel having specific physical and chemical characteristics to enhance the range of refractive power provided by the IOL during accommodation. The fluid or gel is selected such that it cooperates with the power changing lens 110 in providing a sufficient range of accommodation of up to at least 3 diopters, preferably up to at least 5 diopters, preferably up to at least 10 diopters and most preferably up to at least 15 diopters. In a preferred embodiment, the enclosed cavity is filled with the fluid or gel before implantation of the IOL 100 into the capsular bag 40 of the eye and, in a more preferred embodiment, the cavity is filled with the fluid or gel in the manufacture of the IOL 100.

FIGS. 4A-4F and 8-10 more clearly depict the location of the fluid or gel (213, 313, 413, 513) contained within the power changing lens (210, 310, 410, 510). In one preferred embodiment the enclosed cavity defined by the walls of the lens chamber 112 is filled with a fluid, such as a gas or a liquid, having low viscosity at room temperature and a high refractive index. In a preferred embodiment, the fluid (213, 313, 413, 513) is a liquid having a viscosity of 1,000 cP or less at 23° C. and a refractive index of at least 1.46, 1.47, 1.48, or 1.49. The fluid may be a polymer, preferably a silicone polymer, and more preferably a phenyl siloxane polymer, such as a vinyl-terminated phenyl siloxane polymer or a vinyl-terminated diphenyl siloxane polymer. Preferably in embodiments where the fluid is made of a polymer, the polymer is preferably not crosslinked and the polymer may be linear or branched. Where the fluid is a vinyl-terminated phenyl siloxane polymer or diphenyl siloxane polymer, the vinyl groups may be reacted to form other moieties that do not form crosslinkages.

In accordance with one embodiment, fluid (213, 313, 413, 513) may be a polyphenyl ether (“PPE”), as described in U.S. Pat. No. 7,256,943, entitled “Variable Focus Liquid-Filled Lens Using Polyphenyl Ethers” to Teledyne Licensing, LLC, the entire contents of which are incorporated herein by reference as if set forth fully herein.

In accordance with another embodiment, the fluid (213, 313, 413, 513) may be a fluorinated polyphenyl ether (“FPPE”). FPPE has the unique advantage of providing tunability of the refractive index while being a chemically inert, biocompatible fluid with dispersion properties. The tunability is provided by the increasing or decreasing the phenyl and fluoro content of the polymer. Increasing the phenyl content will effectively increase the refractive index of the FPPE, whereas increasing the fluoro content will decrease the refractive index of the FPPE while decreasing the permeability of the FPPE fluid through the walls of the lens chamber 112.

In another preferred embodiment, the enclosed cavity defined by walls of the lens chamber 112 is filled with a gel (213, 313, 413, 513). The gel (213, 313, 413, 513) preferably has a refractive index of at least 1.46, 1.47, 1.48, or 1.49. The gel may also preferably have a Young's modulus of 20 psi or less, 10 psi or less, 4 psi or less, 1 psi or less, 0.5 psi or less, 0.25 psi or less and 0.01 psi or less. In a preferred embodiment, the gel (213, 313, 413, 513) is a crosslinked polymer, preferably a crosslinked silicone polymer, and more preferably a crosslinked phenyl siloxane polymer, such as a vinyl-terminated phenyl siloxane polymer or a vinyl-terminated diphenyl siloxane polymer. Other optically clear polymer liquids or gels, in addition to siloxane polymers, may be used to fill the enclosed cavity and such polymers may be branched, unbranched, crosslinked or uncrosslinked or any combination of the foregoing.

A gel has the advantages of being extended in molecular weight from being crosslinked, more self-adherent and also adherent to the walls or opposing sides lens chamber 112 than most liquids. This makes a gel less likely to leak through the walls of the power changing lens. In order to obtain the combination of accommodative power with relatively small deformations in the curvature of the power changing lens, the gel (213, 313, 413, 513) is selected so as to have a high refractive index while being made of an optically clear material that is characterized as having a low Young's modulus. Thus, in a preferred embodiment, the gel has a refractive index of 1.46 or greater, preferably 1.47 or greater, 1.48 or greater and most preferably 1.49 or greater. At the same time, the gel preferably has a Young's modulus of 10 psi or less, preferably 5 psi or less, and more preferably 1 psi or less. In a particularly preferred embodiment, the gel has a Young's modulus of 0.5 psi or less, preferably 0.25 psi or less, and most preferably 0.01 psi or less. It is understood that at lower Young's modulus, the gel will present less resistance to deformation and thus the greater the deformation of the power changing lens 110 for a given unit of applied force.

In particularly preferred embodiment, the gel is a vinyl-terminated phenyl siloxane that is produced based on one of the four formulas provided as follows:

Formula 1:

100 parts 20-25 mole % vinyl terminated diphenylsiloxane-dimethylsiloxane copolymer (Gelest PDV 2335).

3 ppm platinum complex catalyst

0.35 pph of phenyl siloxane hydride crosslinker (Nusil XL-106)

Young's modulus of elasticity=0.0033 psi

Formula 2:

100 parts 20-25 mole % vinyl terminated diphenylsiloxane-dimethylsiloxane copolymer (Gelest PDV 2335).

3 ppm platinum complex catalyst

0.4 pph of phenyl siloxane hydride crosslinker (Nusil XL-106)

Young's modulus of elasticity=0.0086 psi

Formula 3:

100 parts 20-25 mole % vinyl terminated diphenylsiloxane-dimethylsiloxane copolymer (Gelest PDV 2335).

3 ppm platinum complex catalyst

0.5 pph of phenyl siloxane hydride crosslinker (Nusil XL-106)

Young's modulus of elasticity=0.0840 psi

Formula 4:

100 parts 20-25 mole % vinyl terminated diphenylsiloxane-dimethylsiloxane copolymer (Gelest PDV 2335).

3 ppm platinum complex catalyst

0.6 pph of phenyl siloxane hydride crosslinker (Nusil XL-106)

Young's modulus of elasticity=2.6 psi

The walls of the lens chamber and the fluid or gel contained within the cavity is preferably selected so as to prevent or reduce the likelihood of the fluid or gel migrating outside of the lens chamber. Thus, in a preferred embodiment, one or both of the power changing lens and the fluid or gel (213, 313, 413, 513) is/are selected from biocompatible materials that optimize the resistance to permeability of the fluid or gel across the power changing lens.

One method of decreasing the permeability of the gel contained inside the cavity and across the power changing lens is to provide a gel that is cross-linked. The degree of cross-linking, however, must be selected and controlled such that, on the one hand, the power changing lens and the gel have a sufficiently low Young's modulus to minimize the resistance of the power changing lens to deformation and, on the other hand, to minimize the permeation of the gel across the power changing lens. Thus, in a preferred embodiment, longer chain polymers that are lightly cross-linked, such as those used for silicone gels, starting with monomers having molecular weights that are greater than 35,000 daltons, preferably greater than 50,000 daltons and, most preferably, at least 70,000 daltons are desired.

In another preferred embodiment, a gel is used having low permeability extractables. Such gels may be formulated by using long chain polymers that are branched.

In a preferred embodiment, one or both of the lens chamber walls and the gel may be made of homo- or co-polymers of phenyl-substituted silicones.

For the lens chamber walls, the crosslinked homo- or co-polymers preferably have a diphenyl content of 5-25 mol %, preferably 10-20 mol % and more preferably 15-18 mol %. Alternatively, for the lens chamber walls, the homo- or co-polymers preferably have a phenyl content of 10-50 mol %, preferably 20-40 mol %, and more preferably 30-36 mol %.

For the gel, the homo- or co-polymers preferably have a diphenyl content of 10-35 mol %, preferably 15-30 mol % and more preferably 20-25 mol %. Alternatively, for the gel, the homo- or co-polymers preferably have a phenyl content of 20-70 mol %, preferably 30-60 mol % and more preferably 40-50 mol %.

In a particularly preferred embodiment, the walls of the lens chamber are made of a crosslinked phenyl siloxane having a diphenyl content of about 15-18 mol % or a phenyl content of about 30-36 mol % and the gel is made of a phenyl siloxane having a diphenyl content of about 20-25 mol % or a phenyl content of about 40-50 mol %. The walls of the lens chamber walls are understood to be more crosslinked than the gel.

In a particularly preferred embodiment, the lens chamber walls are made of a vinyl-terminated phenyl siloxane, most preferably a crosslinked vinyl-terminated phenyl siloxane. Reinforcing agents, such as silica, may also be included in a range of 10-70 mol %, preferably 20-60 mol % and most preferably 30-50 mol %.

The walls of the lens chamber and the fluid or gel contained within the cavity is also preferably selected so as to increase the range of accommodative power that is provided by the lens chamber. In one preferred embodiment, the walls of the lens chamber are made of a material having a lower refractive index than the fluid or gel contained in the enclosed cavity. In one preferred embodiment, the refractive index of the walls of the lens chamber is 1.38 and the refractive index of the gel or fluid contained therein is 1.49.

The differential refractive indices provided by the lens chamber walls and the gel or liquid contained within the lens chamber may be provided by differences in the materials or the composition of the materials used for the lens chamber walls and the gel or liquid.

In one embodiment, both the lens chamber walls and the gel or liquid is made of a phenyl siloxane having different diphenyl or phenyl content. In a preferred embodiment, the lens chamber walls have a diphenyl or phenyl content that is less than that for the gel or liquid. In another preferred embodiment, the walls of the lens chamber may be made of a cross-linked vinyl-terminated phenyl siloxane having a diphenyl content of about 15-18 mol % or a phenyl content of about 30-36 mol % and the gel contained within the lens chamber walls may be made of a vinyl-terminated phenyl-siloxane having a diphenyl content of 20-25 mol % or a phenyl content of 30-36 mol %.

In another embodiment, the differential refractive indices may be provided by providing a dimethyl siloxane for the lens chamber walls and the gel may be a phenyl siloxane having a high diphenyl or phenyl content. In a preferred embodiment, the diphenyl content is at last 20 mol %, at least 25 mol %, at least 30 mol %, at least 35 mol %, and at least 40 mol %. Alternatively, the phenyl content is at least 40 mol %, at least 50 mol %, at least 60 mol %, at least 70 mol % and at least 80 mol %.

In a further embodiment, the differential refractive indices may be provided by a crosslinked fluoro siloxane, such as a 3,3,3-trifluoropropylmethyl siloxane and the gel may be a phenyl siloxane having a high diphenyl or phenyl content. In a preferred embodiment, the diphenyl content is at least 20 mol %, at least 25 mol %, at least 30 mol %, at least 35 mol %, and at least 40 mol %. Alternatively, the phenyl content is at least 40 mol %, at least 50 mol %, at least 60 mol %, at least 70 mol %, and at least 80 mol %.

FIGS. 4A-4F depict alternate embodiments of the two-part IOL device 200A-F in which the shape and configuration of the power changing lens 210 and the primary lens 230 are varied.

In each of these embodiments, certain features remain the same. The power changing lens 210 is depicted as comprising a fluid- or gel-filled lens chamber 212 and a haptic system 214 disposed peripherally of the fluid- or gel-filled lens chamber 212. The lens chamber 212 comprises two opposing surfaces which are divided into a central regions 212 a, 212 b about the central axis A-A (See FIG. 1) and peripheral regions 211 a, 211 b. In a preferred embodiment, the central regions 212 a, 212 b have a gradually increasing thickness radially towards the center of the lens chamber 212 from the peripheral regions 211 a, 211 b.

In a preferred embodiment, the center point of the central regions 212 a, 212 b has a thickness that is two times or more, preferably three times or more, and most preferably 4 times or more than the thickness of the peripheral region 211 a, 211 b. A fluid or gel 213 is contained between the opposing surfaces. In another preferred embodiment, the point of greatest thickness in the central region 212 a, 212 b and the point of least thickness in the peripheral region 211 a, 211 b is a ratio of 2:1 or greater, preferably 3:1 or greater, and most preferably 4:1 or greater. In a preferred embodiment, the thickness at the optical axis or the center of the central region 212 a, 212 b is about 200 microns and the thickness at the peripheral region 211 a, 211 b is about 50 microns. The increased thickness in the central region 212 a, 212 b is provided so as to prevent the opposing surfaces of the lens chamber 212 from buckling when it is deformed in response to accommodation. It is understood that in the various embodiments of the power lens depicted in the figures, the opposing sides preferably has the thickness profiles as described herein and depicted in FIGS. 4A-4F. References to the optical axis or optical axis A-A made herein is understood to mean the line bisecting the center of the IOL device, as shown in FIG. 1.

The opposing surfaces of the lens chamber 212 actuate towards and away from each other when the eye is unaccommodated and accommodated, respectively. The haptic system 214 comprises a peripheral engaging edge 216 and a first coupling surface 218 adjacent the peripheral engaging edge 216. The primary lens assembly 230 comprises a fixed lens 232 and a plurality of centration members 224 disposed about the fixed lens 232. The centration members 224 comprise a distal edge 236 and a second contacting surfaces 238 in sliding contact with the first contacting surfaces 218 of the power changing lens 210.

In a preferred embodiment, the primary lens 230 is substantially thicker than one of the opposing sides lens chamber 212, as measured along the optical axis A-A. In a preferred embodiment, the thickness of each one of the opposing sides lens chamber 212, as along the optical axis A-A is less than ½, preferably less than ⅓, preferably less than ¼, and most preferably less than ⅕ of the thickness of the primary lens 230 at the central optical axis A-A. Because the primary lens 230 is substantially thicker than either one of the opposing sides lens chamber 212, the primary lens 230 has an effective Young's modulus that is substantially greater than either one of the opposing sides of the chamber 212.

Turning now to the various distinguishing features of the two-part IOL devices, reference is made with respect to FIG. 4A of the IOL device 200A in which the primary lens 230 is depicted as comprising a hinge 240 and angled or squared edge 239. The hinge 240 is provided on the centration members 224 to permit it to bend axially, compress radially, or both in response the accommodative forces exerted on the capsular bag. The hinge 240 therefore permits these accommodative forces to act upon the peripheral engaging edge 216 of the power changing lens 210 to actuate the opposing surfaces 212 a, 212 b away from or towards one another. The squared edge 239 is provided to help fix the primary lens assembly to the capsular bag and also to reduce the likelihood of posterior capsular opacification (PCO) from occurring.

FIG. 4B depicts an IOL device 200B that is similar in many respects with FIG. 4A with the exception that the hinge 242 disposed on the centration members 224 is substantially wider so as to provide less resistance to bending, compression or both in response to the accommodative forces exerted on the capsular bag and thus onto the distal edge 236 of the centration member 224. It is understood that for both IOL devices 200A, 200B, the hinge 240 is provided on the surface facing away from the power changing lens 210 and therefore the distal edge 236 pivot in a direction away from the power changing lens 210 when a radially compressive force is applied to the distal edge 236.

FIG. 4C depicts an IOL device 200C in which the primary lens assembly 230 comprises only a squared edge 239 around the periphery of the fixed lens 232. Because the primary lens assembly 230 does not include a hinge, it is expected that this IOL device 200C will be significantly more rigid than the IOL devices 200A and 200B depicted in FIGS. 4A and 4B, respectively.

FIG. 4D depicts an IOL device 200D in which is similar to the IOL device 200B of FIG. 4B with the exception that the hinge 244 is now located on the surface facing the power changing lens 210. Thus, the distal edge 236 will pivot in a direction toward the power changing lens 210 when a radially compressive force is applied to the distal edge 236.

FIG. 4E depicts an IOL device 200E having a greater degree of engagement between the power changing lens 210 and the fixed lens assembly 230. The power changing lens 210 and the fixed lens assembly 230 comprise complementary and interlocking hooks 250, 260 disposed peripherally of the fluid- or gel-filled lens chamber 212 and the fixed lens 232, respectively. Unlike the IOL devices depicted in FIGS. 4A-4D, the power changing lens 210 and the fixed lens assembly 230 are coupled to one another by engagement of the interlocking hooks 250, 260.

FIG. 4F depicts an IOL device 200F in which the power changing lens 210 comprises a circumferential projection 246 downwardly of the peripheral engaging edge 216 to constrain the movement of the fixed lens assembly 230 within the boundary defined by the circumferential portion 246. As a result, it is understood that the fixed lens assembly 230 has a diameter that is less than the diameter defined by the circumferential projection 246.

FIGS. 5-8 depict another embodiment of a two-part IOL device 300 in which the power changing lens 310 is constrained within the boundaries of the fixed lens assembly 350. As shown in FIGS. 5-6, the power changing lens 310 has a roughly disc-shaped outer surface and comprises an enclosed fluid- or gel-filled lens 312, a haptic system 314 and a circumferential peripheral engaging edge 316. The power changing lens 310 further comprises a plurality of circumferential holes 315 disposed peripherally of the enclosed fluid- or gel-filled lens 312. The fluid- or gel-filled lens 312 comprises two opposing surfaces which are divided into central regions 312 a, 312 b and peripheral regions 311 a, 311 b. In a preferred embodiment, the central regions 312 a, 312 b have a gradually increasing thickness radially towards the center of the fluid- or gel-filled lens 312 from the peripheral regions 311 a, 311 b. In a preferred embodiment, the center point of the central regions 312 a, 312 b has a thickness that is two times or more, preferably three times or more, and most preferably 4 times or more than the thickness of the peripheral region 311 a, 311 b. A fluid or gel 313 is contained between the opposing surfaces. In another preferred embodiment, the point of greatest thickness in the central region 312 a, 312 b and the point of least thickness in the peripheral region 311 a, 311 b is a ratio of 2:1 or greater, preferably 3:1 or greater, and most preferably 4:1 or greater. In a preferred embodiment, the thickness at the optical axis or the center of the central region 312 a, 312 b is about 200 microns and the thickness at the peripheral region 311 a, 311 b is about 50 microns. The increased thickness in the central region 312 a, 312 b is provided so as to prevent the opposing surfaces of the fluid- or gel-filled lens 312 from buckling when it is deformed in response to accommodation.

The fixed lens assembly 350 is configured to house and receive the power changing lens 310. The fixed lens assembly 350 comprises a fixed lens 352 centrally disposed and an internal cavity defined by the fixed lens 352, the peripheral side wall 356 and a plurality of radial protrusions 358 projecting inwardly from the top of the peripheral side wall 356. Circumferential grooves or hinges 354 surround the fixed lens 352 and permit pivoting or compression of the peripheral side wall 356 radially inward. A plurality of circumferential holes 359 are provided about the periphery of the fixed lens 352 to permit the flow of aqueous fluid therethrough and into the cavity 375 (FIG. 8B) defined between the power changing lens 310 and the fixed lens assembly 350. The holes 359 also to reduce the material bulk and thus the delivery profile of the fixed lens assembly 350. As shown in FIG. 8B, a space 375 is defined between the power changing lens 310 and the fixed lens assembly 350.

The implantation and assembly of the two-part IOL device 300 follows two steps. In a first step, the fixed lens assembly 350 is inserted into the capsular bag of the eye following capsulhorexis. The fixed lens assembly 350 is centered such that the peripheral side wall 356 engages the circumferential area of the capsular bag that is most densely connected to the zonules and the fixed lens 352 is centered about the optical axis and is in contact with the posterior portion of the capsular bag. In a second step, the power changing lens 310 is inserted into the capsular bag and positioned within the cavity 375 of the fixed lens assembly 350 such that the peripheral engaging edge 316 is in proximity to or in contact with the inner surface 360 of the peripheral side wall 356. Thus, radial compression applied to the peripheral side wall 356 is transmitted to the peripheral engaging edge 316 of the power changing lens 310 such that the fluid- or gel-filled lens increases and decreases in curvature to provide an accommodating response to the relaxation and contraction of the ciliary muscles of the eye, respectively.

FIGS. 9-10 are cross-sectional views of various embodiments of the two-part IOL device.

FIGS. 9A and 9B are cross-sectional view of two alternate embodiments of the two-part IOL device 400A, 400B. In both embodiments, the two-part IOL device comprises a power changing lens 410 and a fixed lens assembly 450. The power changing lens 410 comprises a fluid- or gel-filled lens chamber 412 defined by opposing surfaces and a fluid or gel 413 contained therein. A haptic 414 having an engaging edge 416 is provided peripherally of the lens chamber 412. The fixed lens assembly 450 comprises a centrally-disposed fixed lens 452 and a hinge 454 disposed peripherally of the lens 452. The hinge 454 is preferably disposed on the surface of the fixed-lens assembly 450 facing the power changing lens 410 such that radial compressive forces applied to the circumferential periphery 456 causes it to pivot towards the power changing lens 410 and thus transmit the radially-compressive forces onto the engaging edge 416 of the fluid- or gel-filled lens 412 to effectuate a curvature change in the opposing sides of the fluid- or gel-filled lens chamber 412. The difference between the IOL devices 400A and 400B is that the engaging edge 416 in 400A is in spaced relation to the inner surface 460 of the circumferential periphery 456, whereas the engaging edge 416 in 400B is in contact with the inner surface 460 of the circumferential periphery 456 in the absence of a radially-applied force.

Additionally the IOL devices 400A, 400B are provided with curved surfaces at the points of contact between the power changing lens 410 and the fixed lens assembly 450 to facilitate a sliding movement between them. Thus, in a preferred embodiment, at least the circumferential periphery 456, the engaging edge 416 and the inner surface 460 of the circumferential periphery 456 are curved surfaces.

FIGS. 10A and 10B depict yet another embodiment of the two-part IOL device 500 comprising a power changing lens 510 and a fixed lens assembly 550. The power changing lens 510 comprises a enclosed lens chamber 512 defined by two opposing sides which change in curvature in response to radial forces applied to the periphery 516 of the haptic 514.

The two opposing surfaces are divided into central regions 512 a, 512 b and peripheral regions 511 a, 511 b. In a preferred embodiment, the central regions 512 a, 512 b have a gradually increasing thickness radially towards the center of the enclosed lens chamber 512 from the peripheral regions 511 a, 511 b. In a preferred embodiment, the center point of the central regions 512 a, 512 b has a thickness that is two times or more, preferably three times or more, and most preferably 4 times or more than the thickness of the peripheral region 511 a, 511 b. A fluid or gel 213 is contained between the opposing surfaces. In another preferred embodiment, the point of greatest thickness in the central region 512 a, 512 b and the point of least thickness in the peripheral region 511 a, 511 b is a ratio of 2:1 or greater, preferably 3:1 or greater, and most preferably 4:1 or greater. In a preferred embodiment, the thickness at the optical axis or the center of the central region 512 a, 512 b is about 200 microns and the thickness at the peripheral region 511 a, 511 b is about 50 microns. The increased thickness in the central region 512 a, 512 b is provided so as to prevent the opposing surfaces of the enclosed lens chamber 512 from buckling when it is deformed in response to accommodation. It is understood that in the various embodiments of the power lens depicted in the figures, the opposing sides preferably has the thickness profiles as described herein and depicted in FIGS. 4A-4F.

The fixed-lens assembly 550 comprises a fixed lens 552 that does not change in shape or curvature. An internal cavity is defined by the fixed lens 552 and the circumferential side walls 560. A circumferential hinge 554 provided on the fixed-lens assembly 550 peripherally of the fixed lens 552. The hinge 554 is disposed around the fixed lens 554 and thus permits the peripheral side wall 556 to be compressed radially-inwards in the direction of the arrows B to compress the power changing lens 510 at the contacting periphery 516. This, in turn, causes the opposing sides 512 a, 512 b to curve away from one another. Once the radial forces are no longer applied, the fixed lens assembly is resiliently biased to the expanded and unaccommodated state and the peripheral side wall expands in the direction as indicated by the arrows A.

FIGS. 11A-11F depict various alternative embodiments of the fixed lens assemblies 600A-F that may be used in connection with any one of the fixed lens assembly described herein to form a two-part IOL device of the type described in FIGS. 1-3. As depicted in each of FIGS. 11A-11F, the haptics 614A-F are disposed in a symmetric matter so as to ensure centration of the power changing lens. FIG. 11A depicts a fixed lens assembly 600A having a lens 612A surrounded by four symmetrically disposed tabs 614A. The tabs each comprise an aperture 615A and an engaging edge 616A configured to engage the capsular bag of the patient's eye. FIG. 11B depict a similar arrangement of four haptics 614B, except that the haptics each have a rounded edge 616B and haptic pairs are pointed towards one another. FIG. 11C depict an arrangement of four haptics 614C, also having rounded edges 616C with the haptics being pointed in the same direction.

FIG. 11D depicts a fixed lens assembly 600D comprising a lens 612D and a plurality of haptics 614D each with an aperture 615D disposed therethrough. The haptics 614D further comprise a sizing finger 620 projecting from the outer engaging edge 616D. Implantation of the two-part IOL device typically requires the implantation of the fixed lens assembly first. Once the fixed lens assembly is implanted and positioned, the lens capsule walls may compress the engaging edge 616D and displace the sizing finger 620 toward the lens 612D. The extent to which the sizing finger 620 is displaced toward the lens 612D provides an indication as to the size of the patient's lens capsule so as to permit selection of the appropriately-sized power changing lens that is to be subsequently implanted in the patient's lens capsule.

FIG. 11E depicts yet another fixed lens assembly 600E comprising four haptic tabs 614E each comprising a triangular shaped aperture 615E and a peripheral engaging edge 616E. The significance of the triangular shaped aperture 615E is to reduce the risk of snagging portions of the power changing lens during implantation.

FIG. 11F depicts a further embodiment of the fixed lens assembly 600F comprising a lens 612F and three plate haptics 614F projecting therefrom. Because the configuration of the plate haptics 614F provides for a stiffer haptic, the fixed lens assembly 600F is preferably undersized relative to the lens capsule.

The invention described and claimed herein is not to be limited in scope by the specific preferred embodiments disclosed herein, as these embodiments are intended as illustrations of several aspects of the invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims. 

The invention claimed is:
 1. A two-part accommodating intraocular lens (IOL) device for implantation in a capsular bag of a patient's eye, the IOL device comprising: a primary lens comprising a fixed lens and a centration member disposed peripherally of the fixed lens, the centration member having a circumferential distal edge and a first coupling surface; and a power changing lens comprising a fluid- or gel-filled lens cavity and a haptic system disposed peripherally of the lens cavity, the haptic system having a peripheral engaging edge configured to contact the capsular bag and a second coupling surface facing the first coupling surface; wherein the first and the second coupling surfaces maintain a spaced relationship between the fixed lens and the lens cavity when the power changing lens accommodates as a result of radial compression; and wherein the primary lens and the power changing lens each comprise complementary and interlocking hooks that enable the primary lens and the power changing lens to be coupled to one another by engagement of the complementary and interlocking hooks with each other.
 2. The two-part IOL device of claim 1, wherein the complementary and interlocking hooks of the primary lens and the power changing lens are disposed peripherally of an optical portion of the fluid- or gel-filled lens cavity and an optical portion of the fixed lens, respectively.
 3. The two-part IOL device of claim 1, wherein the spaced relation between the fixed lens and the lens cavity is maintained by angling the centration member toward the haptic system.
 4. A two-part accommodating intraocular lens (IOL) device for implantation in a capsular bag of a patient's eye, the IOL device comprising: a primary lens comprising a fixed lens and a centration member disposed peripherally of the fixed lens, the centration member having a circumferential distal edge and a first coupling surface; a power changing lens comprising a fluid- or gel-filled lens cavity and a haptic system disposed peripherally of the lens cavity, the haptic system having a peripheral engaging edge configured to contact the capsular bag and a second coupling surface facing the first coupling surface; and wherein the first and the second coupling surfaces maintain a spaced relationship between the fixed lens and the lens cavity when the power changing lens accommodates as a result of radial compression; and wherein the first and second coupling surfaces each comprise one member of a complementary and interlocking pair, the complementary and interlocking pair being disposed circumferentially around the fixed lens and the power changing lens, respectively.
 5. The two-part IOL device of claim 4, wherein the power changing lens comprises a circumferential projection that extends to a position peripheral of the primary lens to constrain movement of the primary lens.
 6. The two-part IOL device of claim 5, wherein the circumferential projection extends posteriorly to constrain movement of the primary lens.
 7. The two-part IOL device of claim 5, wherein the circumferential projection constrains movement of the primary lens within a boundary defined by the circumferential projection.
 8. The two-part IOL device of claim 5, wherein the power changing lens comprises two opposing surfaces and at least one of the two opposing surfaces is displaced away from the other of the opposing surfaces upon the application of a radial force along the peripheral engaging edge.
 9. The two-part IOL device of claim 8, wherein fluid or gel moves centrally within the lens cavity upon application of a radial force along the peripheral engaging edge.
 10. The two-part IOL device of claim 8, wherein the fixed lens does not change shape or curvature during accommodation.
 11. The two-part IOL device of claim 10, wherein the fixed lens and the lens cavity are positive power lenses.
 12. The two-part IOL device of claim 8, wherein the two opposing surfaces have central and peripheral regions and a gradually increasing thickness profile from the peripheral to the central regions.
 13. The two-part IOL device of claim 12, wherein the lens cavity changes both shape and curvature during accommodation.
 14. The two-part IOL device of claim 13, wherein the peripheral engaging edge is thicker than the circumferential distal edge.
 15. A two-part accommodating intraocular lens (IOL) device for implantation in a capsular bag of a patient's eye, the IOL device comprising: a primary lens comprising a fixed lens and a centration member disposed peripherally of the fixed lens; and a power changing lens comprising a fluid- or gel-filled lens cavity, a circumferential projection, and a haptic system disposed peripherally of the lens cavity, the haptic system having a peripheral engaging edge configured to contact the capsular bag; wherein the circumferential projection is configured to be disposed peripherally of the primary lens to constrain movement of the primary lens within a boundary defined by the circumferential projection wherein the centration member extends toward the power changing lens such that the fixed lens and the lens cavity are spaced apart from each other; wherein the primary lens and the power changing lens each comprise complementary and interlocking hooks that enable the primary lens and the power changing lens to be coupled to one another by engagement of the complementary and interlocking hooks with each other; and wherein the lens cavity changes both shape and curvature during accommodation that results from application of a radial force along the peripheral edge of the haptic system.
 16. The two-part IOL device of claim 15, wherein the power changing lens comprises two opposing surfaces and at least one of the two opposing surfaces is displaced away from the other of the opposing surfaces upon the application of the radial force along the peripheral engaging edge.
 17. The two-part IOL device of claim 15, wherein a diameter d_(i) of the power changing lens is greater than a diameter d2 of the primary lens.
 18. A two-part accommodating intraocular lens (IOL) device for implantation in a capsular bag of a patient's eye, the IOL device comprising: a primary lens comprising a fixed lens and a centration member disposed peripherally of the fixed lens; and a power changing lens comprising a fluid- or gel-filled lens cavity, a circumferential projection, and a haptic system disposed peripherally of the lens cavity, the haptic system having a peripheral engaging edge configured to contact the capsular bag; wherein the circumferential projection is configured to be disposed peripherally of the primary lens to constrain movement of the primary lens within a boundary defined by the circumferential projection wherein the centration member extends toward the power changing lens such that the fixed lens and the lens cavity are spaced apart from each other; wherein the primary lens and the power changing lens each comprise complementary and interlocking coupling surfaces that enable the primary lens and the power changing lens to be coupled to one another by engagement of the complementary and interlocking coupling surfaces; and wherein the lens cavity changes both shape and curvature during accommodation that results from application of a radial force along the peripheral edge of the haptic system.
 19. The two-part IOL device of claim 18, wherein the complementary and interlocking coupling surfaces are disposed peripherally of an optical portion of the fluid- or gel-filled lens cavity and an optical portion of the fixed lens, respectively.
 20. A method for implanting a two-part IOL device in a capsular bag of a patient's eye, the method comprising: inserting and positioning a power changing lens in the capsular bag of the patient's eye, the power changing lens comprising a fluid- or gel-filled lens cavity and a haptic system disposed peripherally of the lens cavity, the haptic system having a peripheral engaging edge configured to contact the capsular bag and be radially compressed thereby; inserting and positioning a primary lens in the capsular bag of the patient's eye through an incision located in a cornea, the primary lens having a fixed lens and a centration member disposed peripherally of the fixed lens; and engaging first and second coupling surfaces of the centration member and the haptic system that each comprise one member of a complementary and interlocking pair that are disposed circumferentially around the fixed lens and the power changing lens, respectively, such that the primary lens and the power changing lens are coupled together with the fixed lens and the lens cavity being spaced apart from each other and disposed about an optical axis.
 21. The method of claim 20, wherein engaging first and second coupling surfaces of the centration member and the haptic system that each compromise the one member of the complementary and interlocking pair comprises positioning a protrusion of the centration member that extends radially outward in a radially inwardly facing recess of the haptic system.
 22. The method of claim 20, wherein engaging first and second coupling surfaces of the centration member and the haptic system that each compromise the one member of the complementary and interlocking pair comprises positioning a protrusion of the haptic system that extends radially inward in a radially outwardly facing recess of the centration member.
 23. The method of claim 20, wherein engaging first and second coupling surfaces of the centration member and the haptic system that each compromise the one member of the complementary and interlocking pair comprises engaging complementary and interlocking hooks.
 24. A multi-part accommodating intraocular lens (IOL) device for implantation in a capsular bag of a patient's eye, the IOL device comprising: a first lens comprising: a haptic system comprising a peripheral engaging edge configured to contact the capsular bag and a circumferential projection disposed radially inward of the peripheral engaging edge, the circumferential projection at least partially defining a concave space disposed radially inwardly thereof; a cavity supported by the haptic system and having a portion thereof disposed between the peripheral engaging edge and a central optical zone of the first lens and adjacent to the concave space, the cavity enclosed on opposing sides by cavity walls; an optical fluid or gel disposed in the cavity, the optical fluid or gel being shifted upon compression of the peripheral engaging edge by direct contact between and accommodating movement of the capsular bag and at least one of the cavity walls being configured to deflect into the concave space in response thereto to change the power of the first lens; and a second lens comprising: a fixed lens; and a centration structure projecting from a periphery of the fixed lens; and wherein a radially outwardly facing surface of the centration structure of the second lens is engaged with a radially inwardly facing surface of the circumferential projection upon coupling the first lens and the second lens together within the eye following sequential insertion thereof to retain the second lens at least partially within the first lens.
 25. The multi-part accommodating IOL device of claim 24, wherein the radially inwardly facing surface of the circumferential projection of the haptic system of the first lens comprises a bight oriented toward a central optical portion of the first lens.
 26. The multi-part accommodating IOL device of claim 25, wherein the bight is disposed circumferentially about the central optical portion.
 27. The multi-part accommodating IOL device of claim 26, wherein the bight is disposed at least at diametrically opposed sides of the central optical portion.
 28. The multi-part accommodating IOL device of claim 24, wherein the radially outwardly facing surface of the centration structure comprises a curved surface configured to engage the radially inwardly facing surface of the circumferential projection.
 29. The multi-part accommodating IOL device of claim 28, wherein the curved surface comprises a bight oriented away from a central optical portion of the second lens.
 30. The multi-part accommodating IOL device of claim 29, wherein the bight is disposed circumferentially about the centration structure.
 31. The multi-part accommodating IOL device of claim 30, wherein the bight is disposed at least at diametrically opposed sides of the second lens.
 32. The multi-part accommodating IOL device of claim 24, wherein at least a part of the centration structure extends in a direction aligned with a central optical axis of the fixed lens.
 33. The multi-part accommodating IOL device of claim 24, wherein the second lens has a diameter that is less than a diameter of the first lens.
 34. The multi-part accommodating IOL device of claim 24, wherein a thickness of the peripheral engaging edge of the first lens is greater than a thickness of a periphery of the second lens.
 35. The multi-part accommodating IOL device of claim 24, wherein the cavity is disposed entirely radially inwardly of the radially inwardly facing surface of the circumferential projection.
 36. The multi-part accommodating IOL device of claim 24, wherein the radially outwardly facing surface of the centration structure of the second lens and the radially inwardly facing surface of the circumferential projection of the first lens comprise interlocking bights.
 37. The multi-part accommodating IOL device of claim 36, wherein the interlocking bights comprise interlocking hooks.
 38. The multi-part accommodating IOL device of claim 36, wherein the interlocking bights are disposed circumferentially about the first lens and the second lens.
 39. The multi-part accommodating IOL device of claim 38, wherein the interlocking bights are disposed at diametrically opposed sides of the first lens and the second lens. 